Ferrite waveguide circulator with thermally-conductive dielectric attachments

Abstract

The present invention improves the geometry of ferrite circulators in order to increase the average power handling by decreasing the temperature rise in the ferrite and associated adhesive bonds. Embodiments of the present invention utilize dielectric attachments on the sides of the ferrite element, which maximizes the area of contact and minimizes the path length from the ferrite element out to the thermally conductive attachments.

1. A ferrite waveguide circulator, comprising:
 a waveguide structure having an internal cavity, the waveguide structure including a plurality of ports extending from the internal cavity; 
 at least one ferrite element disposed in the internal cavity, said ferrite element including at least one leg having a length dimension, a height dimension, and a width dimension, wherein the length dimension is parallel to the direction of propagation of a signal through the leg of the ferrite element, the height dimension and the width dimension are perpendicular to the direction of propagation of a signal through the leg of the ferrite element, and the height dimension is larger than the width dimension, said at least one leg of the ferrite element having at least two side surfaces and one face surface, wherein said side surfaces extend along the length dimension and the height dimension and the face surface extends along the height dimension and the width dimension; and 
 at least one thermally-conductive dielectric attachment affixed to at least one of said side surfaces of the ferrite element. 
 
     
     
       2. The ferrite waveguide circulator according to  claim 1 , wherein the dielectric attachment is one of boron nitride, aluminum nitride, beryllium oxide, and combinations thereof. 
     
     
       3. The ferrite waveguide circulator according to  claim 1 , wherein the dielectric attachment has a thermal conductivity of at least 0.01 W/(in. 2 ·°C.). 
     
     
       4. The ferrite waveguide circulator according to  claim 1 , wherein the dielectric attachment is less than or equal to about 0.02″ thick for operating ranges about 20 GHz. 
     
     
       5. The ferrite waveguide circulator according to  claim 1 , wherein the dielectric attachment is affixed to one of said side surfaces and covers at least 5% of the surface area of that side surface. 
     
     
       6. The ferrite waveguide circulator according to  claim 1 , wherein the ferrite element includes at least two legs, wherein one dielectric attachment is jointly affixed to a side of each of two legs. 
     
     
       7. The ferrite waveguide circulator according to  claim 1 , further comprising at least one dielectric spacer disposed on an outer surface of the at least one ferrite element. 
     
     
       8. The ferrite waveguide circulator according to  claim 1 , further comprising at least one empirical matching element disposed within the internal cavity. 
     
     
       9. The ferrite waveguide circulator according to  claim 1 , wherein a plurality of thermally-conductive dielectric attachments form a perimeter around the ferrite element. 
     
     
       10. The ferrite waveguide circulator according to  claim 1 , further comprising a least one filler, wherein the filler substantially fills a span between the ferrite element and a proximate opposing wall of the waveguide structure. 
     
     
       11. The ferrite waveguide circulator according to  claim 1 , further comprising at least one thermally-conductive dielectric attachment affixed to at least one of said face surfaces of the ferrite element. 
     
     
       12. The ferrite waveguide circulator according to  claim 11 , further comprising a dielectric transformer, wherein said at least one thermally-conductive dielectric attachment affixed to at least one of said face surfaces is located between said face surface and said dielectric transformer. 
     
     
       13. The ferrite waveguide circulator according to  claim 12 , wherein the at least one thermally-conductive dielectric attachment affixed to at least one of said face surfaces has a first surface area covering the face surface of the ferrite element that exceeds a second surface area of the dielectric transformer that is adjacent to the first surface area. 
     
     
       14. The ferrite waveguide circulator according to  claim 12 , wherein said dielectric attachment covers at least 50% of the surface area of the face surface. 
     
     
       15. A ferrite waveguide circulator, comprising:
 a waveguide structure having an internal cavity, the waveguide structure including a plurality of ports extending from the internal cavity; 
 at least one ferrite element disposed in the internal cavity, said ferrite element including at least one leg having a length dimension, a height dimension, and a width dimension, wherein the length dimension is parallel to the direction of propagation of a signal through the leg of the ferrite element, the height dimension and the width dimension are perpendicular to the direction of propagation of a signal through the leg of the ferrite element, and the height dimension is larger than the width dimension, said at least one leg of the ferrite element having at least two side surfaces and one face surface, wherein said side surfaces extend along the length dimension and the height dimension and the face surface extends along the height dimension and the width dimension; 
 at least one thermally-conductive dielectric attachment affixed to at least one of said face surfaces of the ferrite element; and 
 a quarter-wave dielectric transformer extending from said face surface, wherein the at least one thermally-conductive dielectric attachment has a surface area covering the face surface of the ferrite element that exceeds the surface area of the quarter-wave dielectric transformer. 
 
     
     
       16. The ferrite waveguide circulator according to  claim 15 , further comprising a filler material to eliminate air gaps between the at least one of the surfaces of the ferrite element and the waveguide structure. 
     
     
       17. The ferrite waveguide circulator according to  claim 15 , wherein the dielectric attachment is one of boron nitride, aluminum nitride, beryllium oxide, and combinations thereof. 
     
     
       18. The ferrite waveguide circulator according to  claim 15 , wherein the dielectric attachment has a thermal conductivity of at least 0.01 W/(in. 2 ·°C.). 
     
     
       19. The ferrite waveguide circulator according to  claim 15 , wherein the dielectric attachment is less that or equal to about 0.02″ thick for operating ranges about 20 GHz. 
     
     
       20. The ferrite waveguide circulator according to  claim 15 , wherein said dielectric attachment covers at least 50% of the surface area of the face surface. 
     
     
       21. A system for circulating microwaves in a waveguide, comprising:
 a waveguide structure having an internal cavity forming an input port and one or more output ports; 
 a ferrite element that substantially exclusively couples microwaves from said input port to one of said output ports, wherein the substantially exclusive coupling is responsive to an activation of at least one magnetizable winding associated with said ferrite element, and wherein said ferrite element includes at least one leg having a length dimension, a height dimension, and a width dimension, wherein the length dimension is parallel to the direction of propagation of a signal through the leg of the ferrite element, the height dimension and the width dimension are perpendicular to the direction of propagation of a signal through the leg of the ferrite element, and the height dimension is larger than the width dimension, said at least one leg of the ferrite element having at least two side surfaces and one face surface, wherein said side surfaces extend along the length dimension and the height dimension and the face surface extends along the height dimension and the width dimension; and 
 at least one thermally conductive dielectric attachment affixed to at least one of said side surfaces of the ferrite element so as to conduct thermal energy away from said ferrite element. 
 
     
     
       22. The system according to  claim 21 , wherein the dielectric attachment has a thermal conductivity of at least 0.01 W/(in. 2 ·°C.).